The Formula (1) compounds were previously shown to be potent antiparasiticides. The Formula (1) compounds and Formula (1.1) compound, preparation, compositions, and methods of use are described in WO2012/120399. The (S)-enantiomer of the Formula (1.1) compound is herein referred to as Compound A. Additionally, the crystal form of Compound A (Form A) was described in PCT/US2013/56945. Compound A is also referred to as (S)-1-(5′-(5-(3,5-dichloro-4-fluorophenyl)-5-(trifluoromethyl)-4,5-dihydroisoxazol-3-yl)-3′H-spiro[azetidine-3,1′-isobenzofuran]-1-yl)-2-(methylsulfonyl)ethanone).
The object of the invention is, in particular, to use known parasiticides in order to prepare a composition which is highly effective against both endoparasites and ectoparasites. In many instances, parasiticidal combinations are used as a means of broadening the scope of efficacy on different parasites, generally endoparasites or ectoparasites, including those that may be showing resistance to a single agent. In some cases, the combination provides an unexpected scope of activity against the parasite that would not have been anticipated by the addition of another veterinary agent (i.e., a synergistic effect).